How to do it...

We need to perform the following steps to try this recipe:

1. First, we need to create an object with some fields to be validated:

public class User {

    @NotBlank
    private String name;
    
    @Email
    private String email;
    
    @NotEmpty
    private List<@PositiveOrZero Integer> profileId;

    
    public User(String name, String email, List<Integer> profileId) {
        this.name = name;
        this.email = email;
        this.profileId = profileId;
    }
}

2. Then, we create a UserTest class to validate those constraints:

public class UserTest {
 
    private static Validator validator;
 
    @BeforeClass
    public static void setUpClass() {
        validator = Validation.buildDefaultValidatorFactory()
        .getValidator();
    }
 
    @Test
    public void validUser() {
        User user = new User(
            "elder", 
            "elder@eldermoraes.com", 
            asList(1,2));
 
            Set<ConstraintViolation<User>> cv = validator
            .validate(user);
            assertTrue(cv.isEmpty());
    }
 
    @Test
    public void invalidName() {
        User user = new User(
            "", 
            "elder@eldermoraes.com", 
            asList(1,2));
 
            Set<ConstraintViolation<User>> cv = validator
            .validate(user);
            assertEquals(1, cv.size());
    }

    @Test
    public void invalidEmail() {
        User user = new User(
        "elder",

        "elder-eldermoraes_com", 
        asList(1,2));
 
        Set<ConstraintViolation<User>> cv = validator
        .validate(user);
        assertEquals(1, cv.size());
    } 
 
    @Test
    public void invalidId() {
        User user = new User(
            "elder", 
            "elder@eldermoraes.com", 
            asList(-1,-2,1,2));
 
            Set<ConstraintViolation<User>> cv = validator
            .validate(user);
            assertEquals(2, cv.size());
    } 
}

After this, let's see how the recipe works.